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Sewage and sewerage of farm homes [1928]

Chapter 4: NATURE AND QUANTITY OF SEWAGE
By George M. Warren
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About This Book

Provides practical sanitation principles and step-by-step guidance for disposing of household sewage on farms, defining sewage, sewers, and sewerage while quantifying typical waste. Explains microbial decomposition, the role of air in treatment, and hazards from sewage-borne diseases and parasites with emphasis on preventing contamination of water and food. Describes treatment methods and components such as septic tanks, grease traps, filters, and distribution fields, and stresses design choices based on local conditions. Emphasizes proper construction, routine operation and maintenance, and warns that neglect or improper siting can produce nuisances or health risks.

NATURE AND QUANTITY OF SEWAGE

Under average conditions a man discharges daily about 3½ ounces of moist feces and 40 ounces of urine, the total in a year approximating 992 pounds.[1] Feces consist largely of water and undigested or partially digested food; by weight it is 77.2 per cent water.[2] Urine is about 96,3 per cent water.[2]

[1] Practical Physiological Chemistry, by Philip B. Hawk, 1916, pp. 221, 359.

[2] Agriculture, by P. H. Storer, 1894, vol. 2, p. 70.

The excrements constitute but a small part of ordinary sewage. In addition to the excrements and the daily water consumption of perhaps 40 gallons per person are many substances entering into the economy of the household, such as grease, fats, milk, bits of food, meat, fruit and vegetables, tea and coffee grounds, paper, etc. This complex product contains mineral, vegetable, and animal substances, both dissolved and undissolved. It contains dead organic matter and living organisms in the form of exceedingly minute vegetative cells (bacteria) and animal cells (protozoa). These low forms of life are the active agents in destroying dead organic matter.

The bacteria are numbered in billions and include many species, some useful and others harmful. They may be termed tiny scavengers, which under favorable conditions multiply with great rapidity, their useful work being the oxidizing and nitrifying of dissolved organic matter and the breaking down of complex organic solids to liquids and gases. Among the myriads of bacteria are many of a virulent nature. These at any time may include species which are the cause of well-known infectious and parasitic diseases.